scholarly journals First Report of Web Blight Caused by Rhizoctonia solani on Catharanthus roseus in Louisiana

Plant Disease ◽  
2002 ◽  
Vol 86 (11) ◽  
pp. 1272-1272 ◽  
Author(s):  
G. E. Holcomb ◽  
D. E. Carling
Keyword(s):  
Catharanthus Roseus ◽  
First Year ◽  
Culture Dish ◽  
Madagascar Periwinkle ◽  
First Report ◽  
Bedding Plants ◽  
Leaf Spots ◽  
Rainy Weather ◽  
Pathogenicity Tests ◽  
Web Blight

Web (aerial) blight was observed in field plots of Catharanthus roseus (L.) G. Don (Madagascar periwinkle) during three consecutive summers at the Burden Research Center in Baton Rouge. Leaf spots formed first, followed by a general blighting of leaves and stems that resulted in circular areas of dead plants in the plots. Dead leaves were matted together but remained attached to plants. Mycelia, and occasionally small, brown sclerotia (1 to 3 mm) were observed on blighted foliage. During the first year, only prostrate-growing cultivars belonging to the Mediterranean series of C. roseus were infected, but in 2001 and 2002 upright-growing cultivars as well as those with prostrate growth habit became infected. The disease occurred in July and August during periods of hot, humid, and rainy weather. Among 52 cultivars in the 2001 trial, only ‘Tropicana Pink’, ‘Tropicana Rose’ and ‘Stardust Orchid’ were disease free. A Rhizoctonia sp. was consistently isolated from diseased plants and further characterized as R. solani Kühn AG-1 based on its multinucleate cells and hyphal anastomosis with several AG-1 tester isolates. On potato dextrose agar, colonies displayed morphologies with characteristics of AG-1 IA and AG-1 IB, therefore, identification to AG subgroup was not made. Mature colonies ranged from light tan to brown and produced sclerotia, individually or in clumps, at the edge of the culture dish. Pathogenicity tests were performed by placing agar blocks, taken from the margins of 7-day-old cultures, on stems of eight healthy Madagascar periwinkle plants (15 to 20 cm tall). Inoculated and noninoculated control plants were held in a dew chamber at 26°C for 3 days and then moved to a greenhouse. Leaves on all inoculated plants developed water-soaked spots that turned dark brown or black prior to death, whereas noninoculated plants remained healthy. R. solani was reisolated from inoculated plants and its cultural characteristics were similar to those of the original isolate. Web blight occurs in Louisiana on Madagascar periwinkle used as landscape bedding plants, but has not been observed on container-grown plants. Web blight caused by R. solani AG-1 was previously reported on Madagascar periwinkle from Alabama (1). R. solani AG-1 has been reported previously as causing web blight in Louisiana on rosemary (2), dianthus (4), and verbena (3). To our knowledge, this is the first report of web blight on Madagascar periwinkle (C. roseus) in Louisiana. References: (1) A. K. Hagan and J. M. Mullen. Plant Dis. 77:1169, 1993. (2) G. E. Holcomb. Plant Dis. 76:859, 1992. (3) G. E. Holcomb and D. E. Carling. Plant Dis. 84:492, 2000. (4) G. E. Holcomb and D. E. Carling. Plant Dis. 84:1344, 2000.

scholarly journals First Report of Web Blight on Yellow-Sage (Lantana camara) Caused by Rhizoctonia solani in Europe

Plant Disease ◽  
2003 ◽  
Vol 87 (7) ◽  
pp. 875-875 ◽  
Author(s):  
A. Garibaldi ◽  
A. Minuto ◽  
D. Bertetti ◽  
R. Nicoletti ◽  
M. L. Gullino
Keyword(s):  
United States ◽  
Rhizoctonia Solani ◽  
The United States ◽  
The Philippines ◽  
Lantana Camara ◽  
First Report ◽  
Leaf Spots ◽  
Entire Plant ◽  
Pathogenicity Tests ◽  
Web Blight

Lantana camara is increasingly grown in northern Italy as a potted plant and contributes to the diversification of offerings in the ornamental market. During the spring of 2001, selections of L. camara cuttings growing at a commercial farm located at Albenga (Riviera coast) exhibited tan leaf spots of irregular size and shape. Spots were at first isolated, 4 to 8 mm in diameter, and later coalesced and affected the entire plant. Heavily infected leaves, stems, and branches became blighted and were killed. Infected rooted cuttings also eventually died. Diseased cuttings showed a progressive reduction (to less than 20%) in rooting ability. Isolations from infected leaves and stems on potato dextrose agar (PDA), supplemented with 100 mg/liter of streptomycin sulphate, consistently yielded a fungus with mycelial and cultural characteristics resembling Rhizoctonia solani. The fungal isolates were further characterized as R. solani Kühn AG-4 based on hyphal anastomoses with several AG-4 tester isolates. Pathogenicity tests were performed by placing 5-day-old-fungal mycelial plugs, grown on PDA, at the base of five healthy yellow-sage stems and holding plants in a dew chamber at 18 to 22°C. After 2 days, foliage blight appeared on leaves of inoculated plants, and after 3 days, stems also became infected and entire plants wilted. Five noninoculated plants remained healthy. The fungal pathogen was reisolated from all inoculated plants. R. solani has been observed on L. camara in the United States (1) and the Philippines (2). To our knowledge, this is the first report of R. solani on L. camara in Europe. References: (1) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St. Paul, MN, 1989. (2) F. T. Orillo and R. B. Valdez. Philipp. Agric. A. 42:292, 1958.

scholarly journals First Report of Sclerotium rolfsii on Catharanthus roseus

Plant Disease ◽  
2000 ◽  
Vol 84 (2) ◽  
pp. 200-200
Author(s):  
G. E. Holcomb
Keyword(s):  
Catharanthus Roseus ◽  
Fungal Pathogen ◽  
Baton Rouge ◽  
Sclerotium Rolfsii ◽  
The United States ◽  
Madagascar Periwinkle ◽  
Basal Stem Rot ◽  
First Report ◽  
Pathogenicity Tests ◽  
Stem Necrosis

Wilt, blight, and stem necrosis were observed on Catharanthus roseus (L.) G. Don ‘Mediterranean Deep Rose’ (MDR) plants (Madagascar or rose periwinkle) in August 1999 at Burden Research Plantation in Baton Rouge, LA. MDR was the only prostrate-form cultivar and the only cultivar of 11 that was diseased. Twelve of twenty-four plants of cv. MDR were killed in the trial planting. White mycelia and small (1 mm diameter) light brown sclerotia were present at the base of infected plants. The suspect fungus was isolated consistently on acidified water agar and maintained on acidified potato dextrose agar (APDA). Pathogenicity tests were done by pipetting 1 ml of blended inoculum (contents of one 7-day-old plate culture grown on APDA in 100 ml of deionized water) at the base of nine 15-cm-tall Madagascar periwinkle plants. Inoculated and noninoculated plants were held in a dew chamber for 3 days at 28°C and placed in a greenhouse where temperatures ranged between 25 and 31°C. All inoculated plants showed wilt, blight, and basal stem rot after 3 days and were dead after 10 days. Noninoculated plants remained symptomless. The fungal pathogen was identified as Sclerotium rolfsii Sacc. and was reisolated from inoculated plants. The fungus was previously reported on Lochnera rosea (L.) Rchb. (=C. roseus) from Taiwan (1). This is the first report of the occurrence of S. rolfsii on Madagascar periwinkle in the United States. Reference: (1) K. Goto. Trans. Nat. Hist. Soc. Formosa 23:37, 1933.

scholarly journals Catharanthus roseus, an Experimental Host Plant for the Citrus Strain of Xylella fastidiosa

Plant Disease ◽  
2001 ◽  
Vol 85 (3) ◽  
pp. 246-251 ◽  
Author(s):  
P. B. Monteiro ◽  
J. Renaudin ◽  
S. Jagoueix-Eveillard ◽  
A. J. Ayres ◽  
M. Garnier ◽  
...  
Keyword(s):  
Catharanthus Roseus ◽  
Xylella Fastidiosa ◽  
Post Inoculation ◽  
Herbaceous Plant ◽  
Protein Subunit ◽  
Madagascar Periwinkle ◽  
Experimental Host ◽  
Leaf Chlorosis ◽  
Pathogenicity Tests ◽  
Leaf Deformation

We verified by pathogenicity tests that the herbaceous plant Catharanthus roseus (Madagascar periwinkle) can be used as an experimental host for the strain of Xylella fastidiosa that causes citrus variegated chlorosis (CVC). Plants were mechanically inoculated with CVC strain 9a5c, the genome of which was recently sequenced. Plants were inoculated with the virulent 8th passage (9a5c-8) and the 51st passage (9a5c-51). Leaf deformation and stunting were seen 2 months after inoculation on 18 of 21 plants with 9a5c-8 and 8 of 21 plants with 9a5c-51. The plants were infected with X. fastidiosa as shown by polymerase chain reaction. The bacterium could be reisolated from all plants tested, showing that CVC-X. fastidiosa multiplied and moved systemically in C. roseus plants causing dysfunction in plant growth. The disease symptoms evolved within 4 months post-inoculation to a severe leaf chlorosis in all inoculated plants. The localization of X. fastidiosa in the xylem was verified by immunofluorescence. Genes coding for proteins with homologies to plant sterol-C-methyltransferase, a transketolase-like protein, subunit III of photosystem I, and a desiccation protectant protein were found to be differentially expressed in symptomatic C. roseus plants as a response to infection with X. fastidiosa in comparison to healthy plants. A tentative correlation between the pattern of expression of these C. roseus genes with the mechanism of pathogenicity of X. fastidiosa is discussed.

scholarly journals First Report of Leaf Spot Caused by Alternaria alternata on Kiwifruit in Italy

Plant Disease ◽  
1999 ◽  
Vol 83 (5) ◽  
pp. 487-487 ◽  
Author(s):  
L. Corazza ◽  
L. Luongo ◽  
M. Parisi
Keyword(s):  
New Zealand ◽  
Alternaria Alternata ◽  
Leaf Spot ◽  
Southern Italy ◽  
Morphological Characteristics ◽  
Potato Dextrose Agar ◽  
First Report ◽  
Leaf Spots ◽  
Detached Leaves ◽  
Pathogenicity Tests

A leaf spot of kiwifruit (Actinidia deliciosa (A. Chev.) C. F. Liang & A. R. Ferg.) leaves was recently observed on plants of the cultivar Hayward in an orchard near Salerno, in southern Italy. The affected plants showed early severe defoliation. The fungus isolated from the infected leaves was identified as Alternaria alternata (Fr.:Fr.) Keissl., based on conidial morphological characteristics. Pathogenicity tests were made by inoculating detached leaves of male pollinator cultivar Tomuri and the female cultivars Hayward and Bruno with a 7-mm disk taken from actively growing cultures of the fungus on potato dextrose agar (PDA). After 14 days, necrotic leaf spots developed and A. alternata was consistently isolated from the inoculated leaves. A. alternata has been observed as a pathogen on leaves and fruits in New Zealand. In the Mediterranean, it has been reported in Israel (2) and in the island of Crete (1). This is the first report of Alternaria leaf spot on kiwifruit in Italy. References: (1) V. A. Bourbos and M. T. Skoudridakis. Petria 7:111, 1997. (2) A. Sive and D. Resnizky. Alon Hanotea 41:409, 1987.

scholarly journals First Report of Stem and Leaf Anthracnose on Blueberry Caused by Colletotrichum gloeosporioides in China

Plant Disease ◽  
2013 ◽  
Vol 97 (6) ◽  
pp. 845-845 ◽  
Author(s):  
C. N. Xu ◽  
Z. S. Zhou ◽  
Y. X. Wu ◽  
F. M. Chi ◽  
Z. R. Ji ◽  
...  
Keyword(s):  
Colletotrichum Gloeosporioides ◽  
Morphological Characteristics ◽  
Its Region ◽  
Pathogenic Fungi ◽  
Molecular Characteristics ◽  
First Report ◽  
Potted Plants ◽  
Leaf Spots ◽  
Pathogenicity Tests ◽  
Highbush Blueberries

Blueberry (Vaccinium spp.) is becoming increasingly popular in China as a nutritional berry crop. With the expansion of blueberry production, many diseases have become widespread in different regions of China. In August of 2012, stem and leaf spots symptomatic of anthracnose were sporadically observed on highbush blueberries in a field located in Liaoning, China, where approximately 15% of plants were diseased. Symptoms first appeared as yellow to reddish, irregularly-shaped lesions on leaves and stems. The lesions then expanded, becoming dark brown in the center and surrounded by a reddish halo. Leaf and stem tissues (5 × 5 mm) were cut from the lesion margins and surface-disinfected in 70% ethanol for 30 s, followed by three rinses with sterile water before placing on potato dextrose agar (PDA). Plates were incubated at 28°C. Colonies were initially white, becoming grayish-white to gray with yellow spore masses. Conidia were one-celled, hyaline, and cylindrical with rounded ends, measuring 15.0 to 25.0 × 4.0 to 7.5 μm. No teleomorph was observed. The fungus was tentatively identified as Colletotrichum gloeosporioides (PenZ.) PenZ & Sacc. (teleomorph Glomerella cingulata (Stoneman) Spauld. & H. Schrenk) based on morphological characteristics of the colony and conidia (1). Genomic DNA was extracted from isolate XCG1 and the internal transcribed spacer (ITS) region of the ribosomal DNA (ITS1–5.8S-ITS2) was amplified with primer pairs ITS1 and ITS4. BLAST searches showed 99% identity with C. gloeosporioides isolates in GenBank (Accession No. AF272779). The sequence of isolate XCG1 (C. gloeosporioides) was deposited into GenBank (JX878503). Pathogenicity tests were conducted on 2-year-old potted blueberries, cv. Berkeley. Stems and leaves of 10 potted blueberry plants were wounded with a sterilized needle and sprayed with a suspension of 105 conidia per ml of sterilized water. Five healthy potted plants were inoculated with sterilized water as control. Dark brown lesions surrounded by reddish halos developed on all inoculated leaves and stems after 7 days, and the pathogen was reisolated from lesions of 50% of inoculated plants as described above. The colony and conidial morphology were identical to the original isolate XCG1. No symptoms developed on the control plants. The causal agent of anthracnose on blueberry was identified as C. gloeosporioides on the basis of morphological and molecular characteristics, and its pathogenicity was confirmed with Koch's postulates. Worldwide, it has been reported that blueberry anthracnose might be caused by C. acutatum and C. gloeosporioides (2). However, we did not isolate C. acutatum during this study. To our knowledge, this is the first report of stem and leaf anthracnose of blueberry caused by C. gloeosporioides in China. References: (1) J. M. E. Mourde. No 315. CMI Descriptions of Pathogenic Fungi and Bacteria. Kew, Surrey, UK, 1971. (2) N. Verma, et al. Plant Pathol. 55:442, 2006.

scholarly journals Outbreak of Black Root Rot in Catharanthus roseus Caused by Thielaviopsis basicola

Plant Disease ◽  
1999 ◽  
Vol 83 (4) ◽  
pp. 396-396
Author(s):  
R. J. McGovern ◽  
T. E. Seijo
Keyword(s):  
Catharanthus Roseus ◽  
Root Rot ◽  
Selective Medium ◽  
Thielaviopsis Basicola ◽  
Madagascar Periwinkle ◽  
Black Root Rot ◽  
Potting Medium ◽  
Rainy Weather ◽  
Bedding Plant ◽  
Blue Shade

A bedding plant grower in southwest Florida reported severe losses in potted Catharanthus roseus (Madagascar periwinkle) transplanted on various dates in December 1997. Symptoms included yellowing of lower leaves, defoliation, black root rot, and plant death. Thielaviopsis basicola was consistently isolated from blackened roots on a selective medium (1). A disease survey was conducted during mid March 1998 of 7,500 periwinkle plants in the two cultivar series Pacific (cvs. Punch, Red, and White) and Cooler (cvs. Grape, Icy, Peppermint, Pink, and Raspberry). Black root rot symptoms were observed in 21 to 53% of periwinkles transplanted between 3 and 11 December, and in 0 to 19% of plants transplanted between 21 and 29 December. The two cultivar series did not appear to differ in their susceptibility to T. basicola. The fungus was consistently isolated from symptomatic periwinkle roots, from roots of chlorotic violas (Viola cornuta), and from a potting medium used for early December transplanting. Pathogenicity of isolates of T. basicola from periwinkle, viola, and the contaminated medium was investigated. Inocula were produced by growing the fungus on acidified potato dextrose agar for 18 days. Conidia, chlamydospores, and hyphae of T. basicola were suspended in deionized water (100 ml/95 mm culture plate). One milliliter of inoculum suspensions of each of the three isolates was used to inoculate 12 plants of pansy (Viola × Wittrockiana) cv. Majestic Giant Blue Shade. An equal number of plants served as noninoculated controls. In addition, 5 ml of each isolate suspension was used to inoculate three six-plant replications of periwinkle cv. Pink Cooler. Plants were incubated in a controlled environment chamber at day/night temperatures of 24/22°C with a 12-h photoperiod. After 22 days, moderate to severe root discoloration was produced in pansy by the viola isolate of the fungus, while periwinkle and potting medium isolates produced only minimal discoloration. Chlamydospores typical of T. basicola were observed in the roots of all inoculated pansies, and in the roots of one of 12 non-inoculated controls. After 38 days, periwinkle plants were rated for foliar yellowing (0 = no yellowing, to 3 = severe yellowing) and percent defoliation, and fresh weights of shoots and roots were obtained. T. basicola was recovered on the selective medium from roots of all inoculated plants and from 68% of the noninoculated controls, indicating that secondary spread had occurred. All three isolates of the fungus caused yellowing and defoliation, but only the periwinkle and potting medium isolates significantly reduced both shoot and root weights in periwinkle, compared with control plants. T. basicola has not been previously reported to cause black root rot in C. roseus, and a contaminated potting medium used during early December may have provided initial inocula for the outbreak. The unseasonably cool and rainy weather prevalent during winter 1997 and spring 1998 (“El Niño”) may have also promoted the unusual appearance of the disease. Reference: (1) L. P. Specht and G. J. Griffin. Can. J. Plant Pathol. 7:438, 1985.

scholarly journals First Report of Anthracnose Caused by Colletotrichum gloeosporioides on Schefflera actinophylla in China

Plant Disease ◽  
2013 ◽  
Vol 97 (7) ◽  
pp. 998-998
Author(s):  
J. Huang
Keyword(s):  
Dna Sequence ◽  
Species Complex ◽  
Colletotrichum Gloeosporioides ◽  
Conidial Suspension ◽  
First Report ◽  
Leaf Spots ◽  
Black Spots ◽  
Pathogenicity Tests ◽  
Colletotrichum Gloeosporioides Species Complex ◽  
And Control

In China, in mild to warm climates, Schefflera actinophylla is commonly grown as a decorative tree in gardens. When mature, it has bright red flowers in inflorescences with up to 20 racemes that develop in summer or early autumn. From 2008 to 2011, lesions were observed on young and mature leaves in several locations in Guangzhou, China. The first symptoms were circular, necrotic areas that usually developed into irregular, dry, brown to reddish brown or black spots. Spots often first appeared at or near the margins of leaves. Reproductive bodies of the pathogen appeared as black specks in leaf spots. Under a 10× magnification, black, needle-like fungal structures (setae) were observed in the centers of spots on the upper leaf surface. A fungus was isolated from the lesion and was identified as Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. based on cultural characteristics and conidial morphology (1). The voucher isolates were deposited in the Institute of Plant Pathology, Zhongkai University of Agriculture and Engineering. C. gloeosporioides is a species complex (2) and there is a degree of unresolved aspects of taxonomy in this species complex. Cultures on potato dextrose agar (PDA) had aerial white mycelium that turned gray to grayish black after 10 days at 25°C and a 12-h photoperiod and produced salmon to orange conidial masses. Brown, 80 to 120 μm long setae were observed in the acervulus. Conidia 14.1 to 18.0 × 4.0 to 6.1 μm in size were hyaline, thin-walled, aseptate, granular inside, clavate to slightly navicular in shape with an obtuse apex and a truncate base. To identify the fungus, a 588-bp segment of the ITS1-5.8S-ITS2 rDNA region was amplified by PCR and sequenced. The DNA sequence was submitted to GenBank as KC207404. A BLAST search of the DNA sequence showed 99% identity with accessions AY266389.1, EF423519.1, and HM575258.1 of C. gloeosporioides. Pathogenicity tests were conducted under greenhouse conditions at 25 ± 2°C. A total of 15 leaves from three 1-year-old S. actinophylla plants were inoculated with mycelial PDA plugs that were placed on 0.5-cm2 leaf wounds and then wrapped with Parafilm. Control leaves were treated similarly except that they were inoculated with PDA plugs without the fungus. No symptoms developed on control leaves after 10 days. Foliar lesions on inoculated leaves closely resembled those observed in the field. C. gloeosporioides was reisolated consistently from inoculated leaves. Pathogenicity was also tested by spraying leaves of potted S. actinophylla plants about 30 cm in height with 10 ml of a conidial suspension (1 × 105 conidia/ml) prepared from 7-day-old PDA cultures grown at 25°C. Leaves sprayed with distilled water were used as controls. Three plants were inoculated in each of two experiments and were incubated at 25°C and 90% relative humidity in a growth chamber. Tiny brown spots started to develop on all inoculated leaves 5 days after inoculation and the progression of symptom development was similar to that observed in the field. Control leaves remained asymptomatic. C. gloeosporioides was reisolated from inoculated leaves. To my knowledge, this is the first report of C. gloeosporioides causing anthracnose on S. actinophylla in China. References: (1) B. C. Sutton. The genus Glomerella and its anamorph Colletotrichum. In: Colletotrichum Biology, Pathology and Control. CAB International, Wallingford, UK, 1992. (2) B. S. Weir et al. The Colletotrichum gloeosporioides species complex. Stud. Mycol. 73:115, 2012.

scholarly journals First Report of Fusicoccum aesculi Causing Leaf Spots of Paeonia suffruticosa in Henan Province, China

Plant Disease ◽  
2012 ◽  
Vol 96 (11) ◽  
pp. 1691-1691
Author(s):  
M. Zhang ◽  
H. Y. Wu ◽  
Y. H. Geng ◽  
S. Q. Yu
Keyword(s):  
New York ◽  
Leaf Spot ◽  
Its Region ◽  
Henan Province ◽  
Paeonia Suffruticosa ◽  
Tree Peony ◽  
First Report ◽  
Leaf Spots ◽  
Pathogenicity Tests ◽  
Fusicoccum Aesculi

Tree peony (Paeonia suffruticosa) is regarded as the national flower of China and is cultivated throughout the country. In early August 2010, a moderately severe leaf spot was observed on tree peony cultivated in a garden of Zhengzhou, Henan Province, where approximately 15% of trees were diseased. In 2011, a less damaging leaf spot was also observed in another area of the city with approximately 10% of trees diseased. Early symptoms appeared as small, round, pale-brown lesions on the leaves. Lesions expanded into 5- to 20-mm-diameter spots that were elliptical or irregular, brown to dark brown. A fungus was consistently isolated from the leaf spots on potato dextrose agar (PDA) in grey-black colonies, but produced few pycnidia. Black pycnidia were ostiolate, globose, papillate, formed in uniloculate or multiloculate stromata that were immersed in the leaf, and became erumpent at maturity. Conidiophores or conidiogenous cells were hyaline and cylindrical. Conidia were hyaline, granular, fusoid to ellipsoid, aseptate, with a sub-truncate base, and 20 to 28 × 4.5 to 7.5 μm (mean dimensions of 50 conidia: 24.5 × 5.2 μm). The pathogen was identified as Fusicoccum aesculi, anamorphic stage of Botryosphaeria dothidea, on the basis of morphology (2). The identity of the fungus was confirmed to be F. aesculi by DNA sequence analysis of the internal transcribed spacer (ITS) region (GenBank Accession No. JQ323001), which was 100% identical to those of other F. aesculi isolates (GenBank Accession Nos. GU997686.1 and GU723469.1) (1). Pathogenicity tests were done by inoculating each of 10 leaves on one 7-year-old tree with a mycelial plug (0.5 cm diameter) harvested from the periphery of a 7-day-old colony. An equal number of leaves on the same tree, serving as controls, were mock-inoculated with plugs of PDA medium. Inoculated leaves were covered with plastic for 24 h to maintain high relative humidity and incubated at about 25°C. The plugs were removed after 48 h. After 7 days, 80% of the inoculated leaves showed symptoms identical to those observed in the field under natural conditions, whereas controls remained symptom-free. Reisolation of the fungus from lesions on inoculated leaves confirmed that the causal agent was F. aesculi. Pathogenicity tests were repeated on the other two trees by the same methods with the same results. To our knowledge, this is the first report of F. aesculi infecting P. suffruticosa in China. References: (1) S. Mohali et al. Mycol. Res. 110:405, 2006. (2) B. C. Sutton. The Coelomycetes. CABI Publishing, New York, 1980.

scholarly journals First Report of Web Blight on Verbena Caused by Rhizoctonia solani

Plant Disease ◽  
2000 ◽  
Vol 84 (4) ◽  
pp. 492-492 ◽  
Author(s):  
G. E. Holcomb ◽  
D. E. Carling
Keyword(s):  
Rhizoctonia Solani ◽  
Fungal Pathogen ◽  
Baton Rouge ◽  
Anastomosis Group ◽  
First Report ◽  
Foliage Blight ◽  
Pathogenicity Tests ◽  
Stem Lesions ◽  
Web Blight ◽  
Branch Death

Web blight was observed on verbena (Verbena × hybrida) during July 1999 in a cultivar trial planting at Burden Research Plantation in Baton Rouge, LA. Foliage blight, stem lesions, and branch death were common symptoms on 12 of 24 cultivars in the trial. Plant death occurred in cvs. Babylon Florena (one of four plants), Purple Princess (two of four plants), and Taylortown Red (two of four plants). Isolations from infected leaves and stems on acidified water agar consistently yielded a fungus with the mycelial and cultural characteristics of Rhizoctonia solani. Pathogenicity tests were carried out by placing 5-day-old fungal mycelial plugs, grown on acidified potato dextrose agar, at the base of healthy verbena stems and holding plants in a dew chamber at 26°C. After 3 days, foliage blight and stem lesions appeared on inoculated plants, and plants were moved to a greenhouse where temperatures ranged from 23 to 32°C. Seven of nine inoculated plants died after 7 days; noninoculated plants remained healthy. The fungal pathogen was reisolated from all inoculated plants. The fungus was identified as R. solani anastomosis group (AG)-1 IB based on multinucleate condition, type of sclerotia produced, and ability to anastomose with R. solani tester isolates of AG-1 IB. This is the first report of web blight on verbena.

scholarly journals First Report of Downy Mildew Caused by Peronospora lamii on Salvia splendens and Salvia coccinea

Plant Disease ◽  
2000 ◽  
Vol 84 (10) ◽  
pp. 1154-1154 ◽  
Author(s):  
G. E. Holcomb
Keyword(s):  
United States ◽  
Downy Mildew ◽  
Pathogenic Fungi ◽  
The United States ◽  
Commonwealth Mycological Institute ◽  
First Report ◽  
Leaf Spots ◽  
Salvia Splendens ◽  
Leaf Surfaces ◽  
Pathogenicity Tests

Angular chlorotic spots were observed on adaxial leaf surfaces of Salvia splendens (scarlet sage cvs. Empire Purple, Empire White, Red Pillar, and Red Hot Sally) and S. coccinea (scarlet or Texas sage cv. Lady in Red) in early May in Baton Rouge area nurseries. Leaf spots sometimes became necrotic and resulted in leaf drop. Abaxial leaf surfaces contained scattered patches of white mycelia with brown spores. Microscopic examination of mycelia revealed irregular dichotomously branched conidiophores with pointed tips and brown oval conidia. Conidiophores averaged 485 × 9 µm and conidia averaged 21 × 18 µm (16 to 26 × 15 to 23 µm) in dimensions. The fungus was identified as Peronospora lamii A. Braun (= P. swinglei Ellis & Everh.) based on these characters and its known occurrence on Salvia spp. and five other genera in the family Lamiaceae (2). Pathogenicity tests were performed by washing conidia from infected leaves into distilled water and mistinoculating S. coccinea cv. Lady in Red and S. splendens cv. Empire Purple with 50,000 spores/ml. Plants were held in a dew chamber at 20°C for 3 days, then moved to a greenhouse where temperatures ranged from 18 to 32°C. Typical angular chlorotic leaf spots developed on inoculated plants within 6 to 8 days and noninoculated plants remained healthy. The fungus did not sporulate under these greenhouse temperatures, but infected leaves that were removed and placed in a moist chamber at 25°C produced conidiophores and brown conidia typical of P. lamii within 2 to 3 days. P. lamii has been reported previously on S. officinalis (3) and S. reflexa (1) in the United States. This is the first report of downy mildew on S. coccinea and S. splendens. Appearance of the disease in retail nurseries that obtained plants from out of state (Arkansas) suggests a widespread occurrence of the disease on these host plants. References: (1) D. F. Farr et al. 1989. Fungi on Plants and Plant Products in the United States. American Phytopathological Society, St. Paul, MN. (2) S. M. Francis. 1981. Peronospora lamii. Descriptions of Pathogenic Fungi and Bacteria No. 688. Commonwealth Mycological Institute, Kew, England. (3) R. T. McMillan and W. R. Graves. Plant Dis. 78:317, 1994.

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